A brushless motor generally includes a control system that controls the excitation of phase windings of the motor. The control system may employ a current control scheme in which a winding is excited until current in the winding exceeds a threshold. On exceeding the threshold, the control system freewheels the winding so as to allow current in the winding to decay. If, however, there is a fault in the control system, the control system may not detect that current in the winding has exceeded the threshold. The control system would then continue to excite the winding and the resulting excessive current may damage the control system and/or the motor.